This invention relates to rack ovens useful for baking or heating food products and, more particularly, to commercial rack ovens such as those used in the bakery industry.
Rack ovens are generally equipped with a fuel-fed heating element and a fan for moving heated air throughout a baking chamber to provide a rapid distribution of hot air over the food product. Commercial ovens of this type include a baking chamber, which is sized to receive a rack having multiple shelves containing products to be baked; a power driven, rotating mechanism to rotate the product as it is being cooked or baked; a combustion system including a single unit burner with a heat exchanger; an exhaust system to eliminate the combustion gases; and a circulating system for directing hot air across the products in the baking chamber. Conventional rack ovens of the type for baking bread generally include a steam generator for the introduction of steam into the oven for brief periods of time, usually at the beginning of the baking process, to impart a desired color and crispness to the crust of the bread.
A particular disadvantage of such ovens is the combustion/exhaust system. There are several main types of combustion/exhaust systems presently used in the manufacture of rack ovens. In one system, air for the combustion mixture is drawn into the system by the action of the flowing gas under pressure. Without any additional means for moving the combustion gases, it is critical that the system employ proper fluing to eliminate the combustion gases. Another system employs an external electrically powered fan which drives air into the combustion system. In this system, ignition of the gas/air mixture is quite often difficult to achieve. Furthermore, as the system accumulates dirt over a period of time, less air is forced into the system while the same amount of gas is being supplied. This causes the gas/air ratio to become progressively richer until delayed combustion occurs resulting in an explosion (commonly known as "puffs"). These explosions are not only hazardous to workers, but can be very destructive to the equipment.
In addition to the above combustion/exhaust system problems, other disadvantages of commercially available ovens are their bulkiness, high manufacturing costs and inefficient heating characteristics.